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Low pressure

I have about a 20 year old rainbird system with six zones, city water fed and 3-4 heads per zone. Every year I have it blown out for winter. This year I am not getting much pressure (heads won't cycle and flow is weak) on any of the zones. Some heads won't even squirt. I replaced the insides of the flowback valve this year because it was leaking last year, but that is the only thing that has changed (and the replacement parts look exactly like the old ones and are same manufacturer (febco). The system always worked great before this. No new construction in the area. Control valves are very close to the house and nothing has changed around the valves or lines there. I am at my wits end. Any suggestions????

Has there been any plumbing done at your house recently. Check to make sure your meter is open all the way. The only way to to this is to close it and then open it again with the hose bib at the house open so you can gauge the pressure or eyeball it. It should be obvious. Also check to see if the Backflow is open all the way. If you are not sure , you are not sure. Check these issues. I will bet you that it is one of these.

No new plumbing has been done in the house and the pressure is the same it it has always been in other parts of the house. The backflow is an atmospheric. How would I check to see if it is open all the way?

Even with out the plumbing situation. Still check the meter turn it off and then turn it on. I have had several customers not aware that somebody shut down the water and then turned it back on. Even if you don't notice a pressure difference at your inside gallons per minute with greater volume (Sprinklers there can be a big difference).

The AVB is not supposed to be under constant pressure. Is it? I am not the AVB Police!!

Low pressure.

Hi, those guys are right. It sounds like a valve isn't open all the way. Here's something I ran across once on an 1 1/2" system. Both ball valves on either side of the backflow were broken. The handle appeared to be on but the balls inside were only open part way giving the system low pressure. That was a very unusual case but a place to look if all else fails. I couldn't tell there was anything wrong with the ball valves until I took them off.